Slashdot is powered by your submissions, so send in your scoop

 


Forgot your password?
Close
typodupeerror
×
Science

Beaming Neutrinos Through Earth? 33

Posted by michael from the death-ray dept.
TheMatt writes: "An article at PhysicsWeb talks about a proposed project by scientists at FermiLab. The project would involve sending a beam of neutrinos 10,000 km through the earth to a detector at SuperKamiokande. The hope is that passing through so much matter would alter the beam enough to better study CP (charge-parity) violation."
This discussion has been archived. No new comments can be posted.

Beaming Neutrinos Through Earth? More

Beaming Neutrinos Through Earth?

Comments Filter:

  • ping time (Score:3, Funny)

    by isorox ( 205688 ) on Tuesday March 12, 2002 @12:01AM (#3147011) Homepage Journal
    If we send a message through the earth, rather then arround, we cut our latency by 1/3 - and thats ignoring and routers enroute. This could revolutionize quake!
    • lets put a wireless neutrino repeater at the core of the earth, that way we don't have any worries about aignal attenuation or mutation.
    • Yes, but the modem is huge.

    • Re:ping time (Score:1, Interesting)

      by Anonymous Coward
      Cutting our latency by 1/3? That's a blanket marketing statement.

      Anywhere from 0 to (Pi-2)/Pi is the correct answer. I hope that's what they'll say in their publicity.
      • Cutting our latency by 1/3?...Anywhere from 0 to (Pi-2)/Pi is the correct answer. I hope that's what they'll say in their publicity.


        Yeah right. I can just hear Larry King doing the interview:


        King: Now I understand this cuts latency by anywhere from zero to Pi minus two over Pi. What a minute, I don't understand that at all! Can you put that in layman's terms?

        Scientist Guy: Well...about one-third, Larry.

        King: There! Now that's an answer I can understand! What's with you scientist guys? OK, now this latency thing - what's that?

  • First impression (Score:2, Interesting)

    by soulcuttr ( 555929 )
    It sounded pretty far-fetched to me at first glance, but judging from the article...
    The SuperKamiokande site has already detected neutrinos from the KEK particle physics lab some 250 kilometres away, although the detector recently suffered an accident and is currently out of commission. There are also plans to send neutrino beams from the CERN particle physics lab in Geneva to the Gran Sasso underground lab 730 kilometres away in Italy, and from Fermilab near Chicago to the Soudan experiment, 710 kilometres away in Minnesota.

    I guess it's just an extension of experiments that are already going on. Will different densities affect how the neutrinos travel (making aiming a difficulty)? Or is that pretty much what they're depending on?

    And maybe a more importantly, what will happen if they miss? (insert wry grin here). I wouldn't hold my breath waiting to find out, though. The article says construction would have to begin by 2006, so there'll definitely be enough time for me to get out of the way.

    -Sou|cuttr

    • Re:First impression (Score:3, Interesting)

      by sigwinch ( 115375 )
      The SuperKamiokande ... detector recently suffered an accident and is currently out of commission.
      "Accident" as in "half its photomultiplier tubes imploded". It will be some time before SuperK is back online.
      Will different densities affect how the neutrinos travel (making aiming a difficulty)?
      They ought to fly straight. (Not that that makes aiming easy!) The parameter of most interest is just the distance between the source and the detector. It is postulated that neutrinos can switch flavors in flight. The more distance they fly, the more chance they have of switching.

    • Re:First impression (Score:3, Informative)

      by mcelrath ( 8027 )
      The article says construction would have to begin by 2006, so there'll definitely be enough time for me to get out of the way.

      Neutrinos interact so weakly that standing in the beamline would not cause you any harm. I have walked through the beamline of the NuTeV Experiment [fnal.gov] (while it was running). Not only that but a beam pointed at Super-K will not be a straight line, it will be more of a cone. At the surface in Japan, where the beam exits the earth, the size of the beam will be ~kilometers.

      -- Bob

      • Re:First impression (Score:3, Interesting)

        by TwP ( 149780 )
        1^2=1; (-1)^2=1; 1^2=(-1)^2; 1=-1; 1=0

        Cute! However, the same logic can be applied to determine that 2=-2, 3=-3, 4=-4, ad infinitum, ad nauseum. In fact, using a third order mapping function you can show that three values (X1,X2,X3) are equivalent. Using a fourth order mapping function you can show that four values are equivalent. And so on . . .

        And now you see the problem of trying to apply a tautology to mapping functions that are not homeomorphic -- i.e. "one to one" and "onto".

        The function X^2=Y involves the loss of some information when mapping X to Y. There are two X values which will resolve to the same Y value. Therefore, the assertion that X1=X2 is correct since the inverse function is ambiguous as to which value of X was used to produce the given Y value. However, to assert that the value is zero you must impose the restriction on your mapping function that it is monotonically increasing or decresing -- i.e. that it is homeomorphic. X^2=Y is not.

        Still, very cute ;)
        • What a complicated way to say it :)
          for that matter , homeomorphism isn't required if I remember correctly as it applies to topological spaces and requires continuity.
          Bijectivity is enough.
          Also, for higher orders, take f(x)=cte and everything equals everything :)
          But anyway, it's more of a logic problem isn't it ?
          donkeys are less than 50m tall, I'm less than 50m tall, therefore I must be a donkey.. no wait.. I really am... err... oh well..
          • Well, it has been a while since I cracked open my abstract algebra book from college, and I seemed to have gotten into a bit of group theory there :/ After consulting my good math Ph.D. wielding friend, Mike, a simple bijection is required to make the assertion that f(x)=f(y) implies x=y.

            I stand corrected. Or at least I sit corrected. "Back to work" the bossman yells as the whip starts a crackin'.
    • Will different densities affect how the neutrinos travel (making aiming a difficulty)? Or is that pretty much what they're depending on?
      I'm no particle physicist, but I believe that density, period (density times distance) is the objective of the long-baseline beam project. Neutrinos can travel through millions of miles of matter like light through glass; they are very hard to scatter because they interact so weakly. On the other hand, it appears that interactions which change the neutrino's flavor without scattering it are much more likely, which is why our early detectors only found 1/3 of the neutrinos we'd expect the Sun to emit from its rate of fusion. (When protons are converted to neutrons, charge and parity are conserved by the emission of a positron and a neutrino; a lot of these electron neutrinos apparently switch flavors to mu and tau neutrinos on their way out of the core.)

      And if they miss? They won't be seeing any neutrinos coming from the source accelerator. If they aimed at you, you'd never notice any more than you notice the millions of solar neutrinos streaking through your body every second like ghost bullets from an etherial machine gun. Hey, they don't even slime you...

  • In the future ... (Score:4, Funny)

    by jquiroga ( 94119 ) on Tuesday March 12, 2002 @12:30AM (#3147132)
    In the future, just after contacting with alien civilizations, we humans will be able to chat with the aliens about all the funny physics experiments we came up with, and ask them if they also carried them out. Imagine the conversations:

    Human: By the way, did you try to beam neutrinos across your planet and gain some insights into the charge-parity violation? We based all our theories on the results of that revolutionary experiment.

    Alien (translated): Yes, being there, done that, half an eon ago. And you got it wrong, see, this "y = i++;" is really "y = ++i". You should have abandoned C long ago.

    Human: Ohhh... I see (damn!)

  • hmmm, time to build a space ship for my kids.
  • i believe that the primary interest is to measure the oscillation between the three types of neutrinos

    this is to help explain the neutrino deficit measured by some detectors that only detect electron neutrinos

    also, some people think that something in the sun is absorbing neutrinos
  • I seem to recall having the following information beaten into my skull: a consequence of the proton-proton chain (the fusion reaction at the core of the sun) was trillions of neutrinos streaming out in all directions - including passing right through us.

    What makes the neutrinos beamed from Earth different than the ones beamed from the sun? And also, would neutrinos/anti-neutrinos interact with each other, and if so, how can they ensure that they won't all annihilate each other?
    • You can distinguish neutrinos from the sun and neutrinos from a generated source by just looking at the source (SuperK is a pointing neutrino telescope - it can tell where they came from).

      The difference between neutrinos from the PP chain in the sun and generated neutrinos is that we will KNOW all the attributes of the neutrinos we generate (i.e. antineutrino vs. neutrino, muon neutrino versus tau neutrino versus electron neutrino, etc.)

      We don't know what the neutrinos from the Sun look like. Just guesses.

      (Neutrinos/ antineutrinos do annihilate. They don't ensure it - it's just that it would very rarely happen. The particle densities here aren't large enough to ensure constant interactions).

  • Since neutrinos interact only weakly with ordinary matter and carry no electrical charge, how in the world do you aim them? All we've got is ordinary matter and electric/magnetic fields, all of which neutrinos ignore.

    Are they planning to do some sort of temporal correlation to tell the difference between a solar and 'man-made' neutrino at the detector? As I recall, the sun produces mostly one type of neutrino. Does the accelerator at Fermilab produce another sort?

    • You don't. You aim a beam of something else, protons, say (in the usual way with magnets) and then smash it into a carefully selected target. The collisions make lots of neutrinos (and other junk, but a few km or rock absorbs that) and they are travelling, pretty much, in the direction of the original beam.
      • The collisions of protons with targets don't make neutrinos, they make pions. Charged pions can be directed magnetically; when they decay to muons, they create neutrinos and when the muons decay to electrons they create still more neutrinos. If the kinetic energy of the decay is small compared to the energy of the original beam, the neutrinos will be travelling in more or less the same direction as the parent particles.
    • Are they planning to do some sort of temporal correlation to tell the difference between a solar and 'man-made' neutrino at the detector?
      The neutrinos from FermiLab are coming from one direction, and all have a very narrow range of energies. The solar neutrinos are coming from another direction, and have lower energies than the beam. So it should be easy to separate.
      As I recall, the sun produces mostly one type of neutrino. Does the accelerator at Fermilab produce another sort?
      It looks like they intend to produce mu-type neutrinos (smash a beam of protons into a target -> you get pions -> focus pions -> pions decay into muons -> muons decay into mu-type neutrinos, e-type neutrinos, and an electron). Knowing the composition of the beam, researchers will see how the composition of the beam changes when it is detected in Japan. We expect to see fewer mu-type neutrinos and more e-type neutrinos. The sun also produces both mu and e-type neutrinos.

      --Bob

  • a new protocol (Score:2, Insightful)

    by rakerman ( 409507 )
    IP over Neutrino.
    Take that RIAA and MPAA! Try to stop filesharing when I can beam my messages through the entire Earth. Ha ha ha!

Slashdot Top Deals

Life is a whim of several billion cells to be you for a while.

Close